• ETRI Journal
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• v.41 no.4
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• pp.452-464
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• 2019

The use of wireless body area networks (WBANs) in healthcare applications has made it convenient to monitor both health personnel and patient status continuously in real time through wearable wireless sensor nodes. However, the heterogeneous and complex network structure of WBANs has some disadvantages in terms of control and management. The software-defined network (SDN) approach is a promising technology that defines a new design and management approach for network communications. In order to create more flexible and dynamic network structures in WBANs, this study uses the SDN approach. For this, a WBAN architecture based on the SDN approach with a new energy-aware routing algorithm for healthcare architecture is proposed. To develop a more flexible architecture, a controller that manages all HUBs is designed. The proposed architecture is modeled using the Riverbed Modeler software for performance analysis. The simulation results show that the SDN-based structure meets the service quality requirements and shows superior performance in terms of energy consumption, throughput, successful transmission rate, and delay parameters according to the traditional routing approach.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1163-1166
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• 2009

전 세계적으로 유헬스 서비스에 대한 관심도가 증가함에 따라 유헬스의 핵심기술 가운데 하나인 무선통신기반의 생체신호 전송기술에 대한 연구 또한 활발히 진행되고 있다. 특히 2000년대부터 시작하여 이미 많은 연구가 진행되어 온 WPAN에서는 Zigbee, Bluetooth, UWB 등의 무선대역을 통하여 생체 신호를 전송하는 연구가 상당히 진행되어 왔으며, 최근에는 IEEE 802.15.6 WBAN에서 MICS, WMTS등과 같은 무선대역을 이용하여 생체신호를 전송하기 위한 연구를 새로이 진행하고 있다. 특히 WLAN이 무선통신기술에 있어 1세대라 하고, WPAN이 2세대라 한다면 WBAN은 3세대 무선통신기술이라고 할 만큼 새로운 시장을 형성할 것으로 예상된다. 따라서 본 고에서는 기존의 WPAN과 최근에 이슈가 되고 있는 WBAN의 무선기술을 통해 생체신호를 전송하기 위한 기술을 분석하고 향후 연구해야 할 내용에 대해 언급하기로 한다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.18-25
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• 2014

A implanted sensor's error probability is more likely to external sensor's error probability by biological characteristic in WBAN. In this paper, we present method that external sensor transmits frame instead of doing implanted sensor's retransmission for improving lifetime of implanted sensors in WBAN. The proposed method, LI(Lifetime Increment) protocol is to add external sensor's id in transmission data frame of a implanted sensor. When the retransmission is required, external sensor that have to registered id in data frame retransmits frame instead of implanted sensors' retransmission. The comparison result shows that the proposed protocol reduces power consumption and improves life time.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.640-647
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• 2014

The WBAN technology means a short distance wireless network which provides each device's interactive communication by connecting devices inside and outside of body located within 3 meters. It is necessary to develop core technology that the WBAN middleware and application service for WBAN sensor network. A device for gathering patient's biometric information was used zigbex of Hanbaek electronics and we designed the message structure which is collected the biometric information. The gateway design and implementation for the WBAN environment. The embedded system was HBE-empos II of Hanbaek electronics and the WBAN network is implemented to BNC and BN that used for hbe-ubi-zigbex. It was confirmed that the proposed sensor gateway could be used for the interconnection of the proposed system with other networks.

• Journal of Internet Computing and Services
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• v.15 no.2
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• pp.9-18
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• 2014

The sensors attached on/in a person are moved since human body frequency changes their activity, therefore in wireless body area networks, nodal mobility and non-line-of-sight condition will impact on performance of networks such as energy efficiency and reliable communication. We then proposed schemes which study on forwarding decisions against frequent change of topology and channel conditions to increase reliable connections and improve energy efficiency. In this work, we control the size of packets, forwarding rate based on ratio of input links and output links at each node. We also robust the network topology by extending the peer to peer IEEE 802.15.4-based. The adaptive topology from chain-based to grid-based can optimal our schemes. The simulation shows that these approaches are not only extending network lifetime to 48.2 percent but also increase around 6.08 percent the packet delivery ratio. The "hot spots" problem is also resolved with this approach.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.802-807
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• 2012

The autothermal reforming of methane to syngas has been carried out in a reactor charged with both a Ni (15 wt%)-Ru (1 wt%)/$Al_2O_3$-MgO metallic monolith catalyst and an electrically-heated convertor (EHC). The standalone type reactor has a start-up time of less than 2 min with the reactant gas of $700^{\circ}C$ fed to the autothermal reactor. The $O_2/CH_4$ and $H_2O/CH_4$ ratio governed the methane conversion and temperature profile of reactor. The reactor temperature increased as the reaction shifted from endothermic to exothermic reaction with decreasing $H_2O/CH_4$ ratio. Also the amount of $CO_2$ in the products increases with increasing $H_2O/CH_4$ ratio due to water gas shift reaction. The 97% of $CH_4$ conversion was obtained and the reactor temperature was maintained $600^{\circ}C$ at the condition of $GHSV=10,000\;h^{-1}$ and feed ratio ($H_2O/CH_4=0.6$ and $O_2/CH_4=0.5$). In this condition, the maximum flow rate of the syngas generated from the reactor charged with 170 cc of the metallic monolith catalyst is $0.94\;Nm^3/h$.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.802-810
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• 2003

In this paper, the modified singular fracture process zone (S-FPZ) model is proposed to consider variation of a fracture criterion for continuous crack propagation in concrete. The fracture properties of the proposed fracture model are strain energy release rate at a micro-crack tip and crack closure stress (CCS) versus crack opening displacement (COD) relationship in the FPZ. The proposed model can simulate the estimated fracture energy of experimental results. The analysis results of the experimental data shows that specimen geometry and loading condition did not affect the CCS-COD relation. But the strain energy release rate is a function of not only specimen geometry but also crack extension. Until 25 mm crack extension, the strain energy release rate is a constant minimum value, and then it increased linearly to the maximum value. The maximum fracture criterion occurred at the peak load for an large size specimen. The fracture criterion remains the maximum value after the peak load. The variation of the fracture criterion is caused by micro-cracking and micro-crack localizing. The fracture criterion of strain energy release rate can simply be the size effect of concrete fracture, and it can be used to quantify the micro-tracking and micro-crack localizing behaviors of concrete.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.56-63
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• 2012

The WBAN technology means a short distance wireless network which provides each device interactive communication by connecting devices inside and outside of body. Standardization on the physical layer, data link layer, network layer and application layer is in progress by IEEE 802.15.6 TG BAN. Wireless body area network is usually configured in energy efficient using sensor and zigbee device due to the power limitation and the characteristics of human body. Wireless sensor network consist of sensor field and sink node. Sensor field are composed a lot of sensor node and sink node collect sensing data. Wireless sensor network has capacity of the self constitution by protocol where placed in large area without fixed position. Mobile sink node distribute energy consumption therefore network life time was increased than fixed sink node. The energy efficient is important matter in wireless body area network because energy resource was limited on sensor node. In this paper we proposed cluster topology algorithm for efficient data transmission in wireless body area network based mobile sink. The proposed algorithm show good performance under the advantage of grid routing protocol and TDMA scheduling that minimized overlap area on cluster and reduced amount of data on cluster header in error prone wireless sensor network based on mobile sink.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4815-4820
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• 2014

As semiconductor chips are on a small scale, large content and high integratation, it is essential to develop the device of pick and place at the system of the semiconductor test handler to ensure its high precision and durability. In this study, inspection equipment frame model of a semiconductor test handler picker was investigated by vibration analysis with the property of the natural frequency and harmonic response. As 3 kinds of analysis case models, the device of pick and place was located at the left side (Case 1), the center (Case 2) and the right side (Case 3) of the upper guideline. The range of natural frequencies until the 6th order on this frame model ranges from 80Hz to 500Hz. As the analysis of the harmonic response when the frame is resonant, Case 2 showed the maximum equivalent stress of 52.802 MPa more than Cases 1 or 3. Case 2 was the most intensive among the three cases. Using the analysis result of this study, the design of the frame model, which can be applied to the safe working environment of the system is believed to be possible.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.265-274
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• 2011

In this paper, it is studied on wide radiating slot antenna's miniaturization for ultra wide-band(UWB) technologies and notch structure to prevent interference between UWB systems and existing wireless systems for using Wi-Fi service of IEEE standards 802.11 a/n. Proposed antenna that wide slot is decreased from $\lambda/2$ to $\lambda/4$ length of resonant frequency has decreased by 72 % compared with conventional antenna. And optimized T-shaped CPW-fed stub has satisfied UWB bandwidth for 3.0~11.8 GHz. Then, creating 2-order Hilbert curve slot line in the stub's patch area, 4.9~5.6 GHz that centered frequency is 5 GHz is eliminated. Finally, the designed antenna constructed on FR4-epoxy has $20{\times}15\;mm^2$ dimension. The measured results that are obtained return loss under -10 dB through 3.2~11.8 GHz without Wi-Fi bandwidth, a linear phase characteristic, a stable group delay, and omnidirectional radiation patterns are presented.